It probably is a form of ezema. Try moisturising creams and perhaps look at your diet. It can be hard to completely cure though. My son has white patches on his face but they only show up in summer when he gets a bit browner. Best to avoid the sun and then no white patches. Take care.
I have that SAME problem! Mine has been there over a year. I don't go tanning because I tan easily, so I am really dark. But these dry white spots on my stomach are all over my stomach and it is getting to my back. I would really appreciate it if I found some answers.